The monoclonal antibody contains VRC01, which effectively blocks viral binding to CD4 cells. Study participants will receive an intravenous infusion of VRC01 at 10 or 30 mg/kg or placebo every 2 months. If the results are positive and a second-generation product and delivery system can be developed, antibody-mediated prevention could also have a major potential role in interrupting maternal to child transmission of HIV resulting from intrapartum exposure or breastfeeding.
Dr. Corey also highlighted a third strategy of HIV vaccine development, one at an earlier stage. Investigators at Johnson & Johnson, in collaboration with the NIAID, HVTN, and other partners, are pursuing a multi-clade approach, one designed to protect against all clades of HIV found around the world. This strategy entails first giving an adenovirus serotype 26–vectored vaccine to prime the immune system, following up with administration of several boosters containing mosaic inserts to increase the response. This vaccine is in phase I studies with no results yet.
Dr. Fauci is not sure which if any of these three approaches will yield a safe and effective vaccine for HIV prevention.
“It’s important to realize that this is a very difficult scientific challenge,” he said. “The body does not readily make an adequate immune response against HIV, unlike virtually any other viral infection. Even the serious ones that cause a degree of morbidity and mortality – smallpox, measles, rubella, polio – ultimately the body does make a good immune response and allows us to clear the virus and leaves us with protection against subsequent exposure to the same virus. We don’t have that advantage with HIV. So it’s going to be difficult to get a safe and effective HIV vaccine, but I think the scientific challenge is worth going after and there’s a reasonable chance we might get there.”
Dr. Corey, Dr. Fauci, and Dr. Bekker reported having no financial conflicts of interest.